The government on Friday banned the sale of six types of sterilizers used in household humidifiers because they may have caused the mysterious hardening of lung tissue that killed nine people this year.

   The Korea Centers for Disease Control and Prevention (KCDC) said detailed tests on animals and examination of people who suffered from the unknown disease revealed a strong connection between the sterilizer and the illness.

   It said the findings, although not conclusive, warrant immediate action and recall of all products from the market.

   The KCDC said that it plans to designate all types of humidifier sterilizers as medical products in the future and will conduct more safety tests on the compounds used to see if they pose health risks.

   The center said manufacturers of other type of sterilizers have been told to stop making their products as a precautionary measure.

   The products cited are sold in many stores across the country and are made up of compounds such as polyhexamethylene guanidine and oligo 2-ethoxy ethoxyethyl guanidium chloride, the state health authority said.

   It said experiments carried out on mice showed the animals'

lung tissue being destroyed in a manner similar to that of people who used the sterilizers.

   The government said that it has found a total of 34 case of the mysterious lung disease this year.

   Local hospitals and clinics have been told to be on the lookout for the people reporting symptoms of the disease.

(Yonhap News)